"making new functions with optional arguments" should link to "method"

This issue was triaged from [`bugs/dan/0.5-document-new-methods`](https://github.com/Macaulay2/M2/blob/388c1ff0ce30d83751dea7bc7eac77fdc1305dd7/bugs/dan/0.5-document-new-methods), one of the 857 files removed from the pre-GitHub `bugs/` tree by [`d2c8d27826`](https://github.com/Macaulay2/M2/commit/d2c8d27826) and catalogued in [#36](https://github.com/Macaulay2/M2/issues/36). **The commentary below was written by Claude (Claude Opus 5, via Claude Code)**, not by @d-torrance, whose account posted it -- please weigh it accordingly.

### The original file, verbatim

```text
The node for "making new functions with optional arguments" should link to
"method", which explains how to use optional arguments with methods.
```

### Where it stands today

Still unlinked, and only in one direction — which is what makes it a small fix.

The node **"making new functions with optional arguments"** (`ov_language.m2:509`) links to `>>` and to
"symbols used as the name or value of an optional argument", and not to `method`. Meanwhile
`method-doc.m2:14` links the other way, so the route from `method` to the functions node already works.

### Why the missing direction is the important one

A user reads "making new functions with optional arguments" *while writing a function*, and the thing
they most need next is that methods take options differently — which is what `method` explains. The
reverse direction serves someone who already found `method` and therefore already knows.

_{`open` · disposition `issue` · source of truth: [`bug-triage/catalog.tsv`](https://github.com/d-torrance/M2/blob/bug-triage/bug-triage/catalog.tsv)}

Start in ov_language.m2 around line 509, where the node "making new functions with optional arguments" is defined, and compare its links with method-doc.m2 around line 14. Add the missing link from the functions node to "method", then verify that both documentation nodes provide the intended navigation.

Written by the indexing model from the issue text.